Wednesday's 2-1 defeat by Germany, following the opening loss to Denmark, leaves one of the pre-tournament favourites and World Cup finalists two years ago without a point at the foot of Group B.
"We know that our game needs to improve. We need to get our routines on the pitch back, the things we are used to, the courage to play," Sneijder told reporters.
"Maybe in that last game, because we know we have to win it, there'll be no other chance. It's all or nothing on Sunday and perhaps we can bring our own football back in that game."
Although their future is out of their hands, the Dutch could still progress to the quarter-finals if they beat Portugal on Sunday and Germany take care of Denmark.
Even then goal difference in the games between the teams on three points would come into play but none of that will matter if Bert van Marwijk's side are unable to solve the numerous problems afflicting them.
Winger Arjen Robben - who stomped off the field and removed his shirt when substituted - highlighted the disjointed nature of the Dutch play with little fluency between defence, midfield and attack.
"There is no cohesion between our lines, there are gaps and we are not connecting and then it is very difficult to recover the ball," he remarked.
"At the moment we are not steady as a team like we were two years ago and there is not one area to blame. We failed as a team.
"Now we have to hope that Germany will do their duty against the Danes and we have to avenge our first two defeats and hope.
"We are not in control now and that doesn't feel good."
GREATER CONCERN
While Robin van Persie's superbly taken second-half goal against Germany will boost his confidence and Robben is always capable of something special, a greater concern will be the way Germany carved open the Dutch defence in the first half with two strikes from Mario Gomez.
Germany coach Joachim Low said he knew there was a chance to exploit spaces left by fit-again central defender Joris Mathijsen and John Heitinga and to beat them individually.
"One thing we did know was that Holland are not so good in one-on-ones in defence and that's how the two goals came about," he said.
"There were little spaces next to Mathijsen and Heitinga and we knew if we could get in there it would be very dangerous for Holland."
The options for Van Marwijk are limited with Klaas-Jan Huntelaar and Rafael van der Vaart now hoping for a start. The coach hinted at frustration over the lack of fresh faces emerging since the 2010 World Cup final defeat by Spain.
"The last two years, we as technical staff spent a lot of time to see if there are fresh names for this team but they have to be available," he said.
"Now we have to work out a plan to beat Portugal with a two goal deficit [in the group]."
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